oracle case statement in where clause with parameter

SQL statement optimization improves database performance and SQL statement database performance In systems with unsatisfactory performance, apart from the fact that the application load exceeds the server's actual processing capacity, it is more

From: http://woainichenxueming.iteye.com/blog/726541I. Optimizing SQL statements in Oracle to improve operational efficiency1. Select the most efficient table name order (valid only in the rule-based optimizer)The Oracle parser processes the table

We have to do not only write SQL, but also to write good performance of SQL statements.(1) Select the most efficient table name order (valid only in the rule-based optimizer):The Oracle parser processes the table names in the FROM clause in a

Select ... for The update statement is a manual lock statement that we often use. Typically, the SELECT statement does not lock the data, preventing other DML and DDL operations from being affected. Also, with the support of the multi-version

(1) Select the most efficient table name order (valid only in rule-based seo/' target= ' _blank ' > Optimizer):The ORACLE parser processes the table names in the FROM clause in a right-to-left order, and the FROM clause is written in the final table

Warm tip: This article is from the Internet, I only do a little processing, not detailed research, only as a later unprepared for the need, if you like to enjoy the turn away.First, the question of the proposedIn the early stage of application

V. Index Optimization Design 1. Manage organization Indexes The index can greatly accelerate the database query speed. The index maps the logical value in the table to a safe RowID, so the index can quickly locate the physical address of the data.

MS SQL Server Query optimization methodThere are many reasons for the slow speed of queries, which are common1, no indexes, or no indexes (this is the most common problem with query slowness, is the flaw in programming)2, I/o throughput is small,

SQL optimization should be adjusted from five aspects:1. Remove unnecessary full table scans for large tables2. cache full table scan for small tables3. Verify the use of optimized Indexes4. Verify the optimized Connection Technology5. minimize the

Oracle SQL Performance 1. ORACLE optimizer:. RULE (based on Rules) B. COST (COST-based) c. CHOOSE (optional) sets the default optimizer. various declarations of the OPTIMIZER_MODE parameter in the ora file, such as RULE, COST, CHOOSE, ALL_ROWS,